Chieko Nakada

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Svend Hollensen

University of Southern Denmark

Robert Kozinets

University of Southern California

DR. RAKESH KUMAR

University of Delhi

Anthony Patterson

Lancaster University Management School

Mourad Touzani

NEOMA Business School

Delphine Dion

ESSEC Business School

Julien Cayla

Nanyang Technological University

Assoc. Prof (Mrs) Hauwa L . Abubakar

Nile University of Nigeria

Dr. Abu Bashar

Gulf University Bahrain

Professor Jochen Wirtz

National University of Singapore

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Papers by Chieko Nakada

ABCA1 dimer–monomer interconversion during HDL generation revealed by single-molecule imaging

Proceedings of the National Academy of Sciences, 2013

The generation of high-density lipoprotein (HDL), one of the most critical events for preventing ... more The generation of high-density lipoprotein (HDL), one of the most critical events for preventing atherosclerosis, is mediated by ATP-binding cassette protein A1 (ABCA1). ABCA1 is known to transfer cellular cholesterol and phospholipids to apolipoprotein A-I (apoA-I) for generating discoidal HDL (dHDL) particles, composed of 100–200 lipid molecules surrounded by two apoA-I molecules; however, the regulatory mechanisms are still poorly understood. Here we observed ABCA1-GFP and apoA-I at the level of single molecules on the plasma membrane via a total internal reflection fluorescence microscope. We found that about 70% of total ABCA1-GFP spots are immobilized on the plasma membrane and estimated that about 89% of immobile ABCA1 molecules are in dimers. Furthermore, an ATPase-deficient ABCA1 mutant failed to be immobilized or form a dimer. We found that the lipid acceptor apoA-I interacts with the ABCA1 dimer to generate dHDL and is followed by ABCA1 dimer–monomer interconversion. This...

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Formation of diffusion barrier in the plasma membrane of the initial segments: study on lipid movements at a single-molecular level

Neuroscience Research, 2000

Single-molecule tracking of membrane molecules: plasma membrane compartmentalization and dynamic assembly of raft-philic signaling molecules

Seminars in Immunology, 2005

Tracking single molecules in the plasma membrane in live cells is becoming a useful technique for... more Tracking single molecules in the plasma membrane in live cells is becoming a useful technique for studying the spatial-temporal control of membrane molecular processes, such as signal transduction and the formation of large molecular complexes. In this review, three topics largely based on recent single-molecule observations are described, with a special emphasis on the results that are considered to be difficult to obtain using conventional methods monitoring the ensemble-averaged behavior of molecules. First, we describe the high-speed single-molecule tracking data, mostly obtained by our group that necessitated the paradigm shift of the plasma membrane structure, from the two-dimensional continuum fluid model to the compartmentalized fluid model. Second, we try to present a synthetic view of the cell membrane, which contains raft and other microdomains as well as being partitioned into small compartments. Furthermore, we present our working hypothesis, based on the literature, how large, stabilized rafts may be formed, after ligation or crosslinking, from small/unstable "reserve" rafts present in the steadystate cells. Finally, we explain our initial application of single-molecule fluorescence imaging for studies of the creation of T-cell receptor signaling complexes (immunological synapses or SMACS), by observing the recruitment of single Lck molecules as an initial approach. This revealed that the assembly of Lck at the T-cell receptor cluster site, observed by conventional fluorescence microscopy, actually represents dynamic concentrations of Lck molecules, entering and exiting the cluster domain rapidly, with the aid of the raft domains.

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Chapter 12 Three-Dimensional Molecular Architecture of the Plasma-Membrane-Associated Cytoskeleton as Reconstructed by Freeze-Etch Electron Tomography

Methods in Cell Biology, 2008

... Here, we list only several of the membrane-related, representative investigations using the f... more

Accumulation of anchored proteins forms membrane diffusion barriers during neuronal polarization

Nature Cell Biology, 2003

The formation and maintenance of polarized distributions of membrane proteins in the cell membran... more The formation and maintenance of polarized distributions of membrane proteins in the cell membrane are key to the function of polarized cells. In polarized neurons, various membrane proteins are localized to the somatodendritic domain or the axon. Neurons control polarized delivery of membrane proteins to each domain, and in addition, they must also block diffusional mixing of proteins between these domains. However, the presence of a diffusion barrier in the cell membrane of the axonal initial segment (IS), which separates these two domains, has been controversial: it is difficult to conceive barrier mechanisms by which an even diffusion of phospholipids could be blocked. Here, by observing the dynamics of individual phospholipid molecules in the plasma membrane of developing hippocampal neurons in culture, we found that their diffusion was blocked in the IS membrane. We also found that the diffusion barrier is formed in neurons 7-10 days after birth through the accumulation of various transmembrane proteins that are anchored to the dense actin-based membrane skeleton meshes being formed under the IS membrane. We conclude that various membrane proteins anchored to the dense membrane skeleton function as rows of pickets, which even stop the overall diffusion of phospholipids, and may represent a universal mechanism for formation of diffusion barriers in the cell membrane.

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PARADIGM SHIFT OF THE PLASMA MEMBRANE CONCEPT FROM THE TWO-DIMENSIONAL CONTINUUM FLUID TO THE PARTITIONED FLUID: High-Speed Single-Molecule Tracking of Membrane Molecules

Annual Review of Biophysics and Biomolecular Structure, 2005

Key Words plasma membrane compartments, actin-based membrane-skeleton fence model, anchored-trans... more Key Words plasma membrane compartments, actin-based membrane-skeleton fence model, anchored-transmembrane protein pickets, single-particle tracking, single fluorescent molecule video imaging ■ Abstract Recent advancements in single-molecule tracking methods with nanometer-level precision now allow researchers to observe the movement, recruitment, and activation of single molecules in the plasma membrane in living cells. In particular, on the basis of the observations by high-speed single-particle tracking at a frame rate of 40,000 frames s −1 , the partitioning of the fluid plasma membrane into submicron compartments throughout the cell membrane and the hop diffusion of virtually all the molecules have been proposed. This could explain why the diffusion coefficients in the plasma membrane are considerably smaller than those in artificial membranes, and why the diffusion coefficient is reduced upon molecular complex formation (oligomerization-induced trapping). In this review, we first describe the high-speed single-molecule tracking methods, and then we critically review a new model of a partitioned fluid plasma membrane and the involvement of the actin-based membrane-skeleton "fences" and anchored-transmembrane protein "pickets" in the formation of compartment boundaries.

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ABCA1 dimer–monomer interconversion during HDL generation revealed by single-molecule imaging

Proceedings of the National Academy of Sciences, 2013

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Formation of diffusion barrier in the plasma membrane of the initial segments: study on lipid movements at a single-molecular level

Neuroscience Research, 2000

Single-molecule tracking of membrane molecules: plasma membrane compartmentalization and dynamic assembly of raft-philic signaling molecules

Seminars in Immunology, 2005

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Chapter 12 Three-Dimensional Molecular Architecture of the Plasma-Membrane-Associated Cytoskeleton as Reconstructed by Freeze-Etch Electron Tomography

Methods in Cell Biology, 2008

... Here, we list only several of the membrane-related, representative investigations using the f... more

Accumulation of anchored proteins forms membrane diffusion barriers during neuronal polarization

Nature Cell Biology, 2003

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PARADIGM SHIFT OF THE PLASMA MEMBRANE CONCEPT FROM THE TWO-DIMENSIONAL CONTINUUM FLUID TO THE PARTITIONED FLUID: High-Speed Single-Molecule Tracking of Membrane Molecules

Annual Review of Biophysics and Biomolecular Structure, 2005

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