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Kobayashi R, Nabika H. Liquid-liquid phase separation induced by crowding condition affects amyloid-β aggregation mechanism. SOFT MATTER 2024; 20:5331-5342. [PMID: 38847095 DOI: 10.1039/d4sm00470a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/11/2024]
Abstract
Liquid-liquid phase separation (LLPS) is common in the aggregation of proteins associated with neurodegenerative diseases. Many efforts have been made to reproduce crowded conditions with artificial polymeric materials to understand the effect of LLPS in physiological conditions with significantly highly concentrated proteins, such as intrinsically disordered proteins. Although the possibility that LLPS is involved in intracellular amyloid-β (Aβ) aggregation, a protein related to the pathogenesis of Alzheimer's disease, has been investigated, the relationship between LLPS and the aggregation of Aβ is poorly characterized. Thus, in this study, we mimicked the intracellular crowding environment using polyethylene glycol and dextran, used commonly as model polymers, to examine the relationship of Aβ with LLPS and aggregation dynamics in vitro. We confirmed that Aβ undergoes LLPS under specific polymer coexistence conditions. Moreover, the addition of different electrolytes modulated LLPS and fibril formation. These results suggest that hydrophobic and electrostatic interactions are the driving forces for the LLPS of Aβ. Similar to the role of the liposome interface, the interface of droplets induced by LLPS functioned as the site for heterogeneous nucleation. These findings offer valuable insights into the complex mechanisms of Aβ aggregation in vivo and may be useful in establishing therapeutic methods for Alzheimer's disease.
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Affiliation(s)
- Ryuki Kobayashi
- Department of Science, Graduate School of Science and Engineering, Yamagata University, 1-4-12, Kojirakawa, Yamagata 990-8560, Japan
| | - Hideki Nabika
- Faculty of Science, Yamagata University, 1-4-12 Kojirakawa, Yamagata 990-8560, Japan.
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2
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Zhang A, Guo Z, Ge G, Liu Z. Insights into In Vivo Environmental Effects on Quantitative Biochemistry in Single Cells. Anal Chem 2023; 95:17246-17255. [PMID: 37963214 DOI: 10.1021/acs.analchem.3c03102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2023]
Abstract
Biomacromolecules exist and function in a crowded and spatially confined intracellular milieu. Single-cell analysis has been an essential tool for deciphering the molecular mechanisms of cell biology and cellular heterogeneity. However, a sound understanding of in vivo environmental effects on single-cell quantification has not been well established. In this study, via cell mimicking with giant unilamellar vesicles and single-cell analysis by an approach called plasmonic immunosandwich assay (PISA) that we developed previously, we investigated the effects of two in vivo environmental factors, i.e., molecular crowding and spatial confinement, on quantitative biochemistry in the cytoplasm of single cells. We find that molecular crowding greatly affects the biomolecular interactions and immunorecognition-based detection while the effect of spatial confinement in cell-sized space is negligible. Without considering the effect of molecular crowding, the results by PISA were found to be apparently under-quantitated, being only 29.5-50.0% of those by the calibration curve considering the effect of molecular crowding. We further demonstrated that the use of a calibration curve established with standard solutions containing 20% (wt) polyethylene glycol 6000 can well offset the effect of intracellular crowding and thereby provide a simple but accurate calibration for the PISA measurement. Thus, this study not only sheds light on how intracellular environmental factors influence biomolecular interactions and immunorecognition-based single-cell quantification but also provides a simple but effective strategy to make the single-cell analysis more accurate.
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Affiliation(s)
- Anqi Zhang
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, 163 Xianlin Avenue, Nanjing 210023, China
| | - Zhanchen Guo
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, 163 Xianlin Avenue, Nanjing 210023, China
| | - Ge Ge
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, 163 Xianlin Avenue, Nanjing 210023, China
| | - Zhen Liu
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, 163 Xianlin Avenue, Nanjing 210023, China
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Abelenda-Núñez I, Ortega F, Rubio RG, Guzmán E. Anomalous Colloidal Motion under Strong Confinement. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2302115. [PMID: 37116105 DOI: 10.1002/smll.202302115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2023] [Revised: 04/13/2023] [Indexed: 06/19/2023]
Abstract
Diffusion of biological macromolecules in the cytoplasm is a paradigm of colloidal diffusion in an environment characterized by a strong restriction of the accessible volume. This makes of the understanding of the physical rules governing colloidal diffusion under conditions mimicking the reduction in accessible volume occurring in the cell cytoplasm, a problem of a paramount importance. This work aims to study how the thermal motion of spherical colloidal beads in the inner cavity of giant unilamellar vesicles (GUVs) is modified by strong confinement conditions, and the viscoelastic character of the medium. Using single particle tracking, it is found that both the confinement and the environmental viscoelasticity lead to the emergence of anomalous motion pathways for colloidal microbeads encapsulated in the aqueous inner cavity of GUVs. This anomalous diffusion is strongly dependent on the ratio between the volume of the colloidal particle and that of the GUV under consideration as well as on the viscosity of the particle's liquid environment. Therefore, the results evidence that the reduction of the free volume accessible to colloidal motion pushes the diffusion far from a standard Brownian pathway as a result of the change in the hydrodynamic boundary conditions driving the particle motion.
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Affiliation(s)
- Irene Abelenda-Núñez
- Departamento de Química Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Ciudad Universitaria s/n., Madrid, 28040, Spain
| | - Francisco Ortega
- Departamento de Química Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Ciudad Universitaria s/n., Madrid, 28040, Spain
- Unidad de Materia Condensada, Instituto Pluridisciplinar, Universidad Complutense de Madrid, Paseo Juan XXIII 1., Madrid, 28040, Spain
| | - Ramón G Rubio
- Departamento de Química Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Ciudad Universitaria s/n., Madrid, 28040, Spain
| | - Eduardo Guzmán
- Departamento de Química Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Ciudad Universitaria s/n., Madrid, 28040, Spain
- Unidad de Materia Condensada, Instituto Pluridisciplinar, Universidad Complutense de Madrid, Paseo Juan XXIII 1., Madrid, 28040, Spain
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Yanagisawa M, Watanabe C, Yoshinaga N, Fujiwara K. Cell-Size Space Regulates the Behavior of Confined Polymers: From Nano- and Micromaterials Science to Biology. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:11811-11827. [PMID: 36125172 DOI: 10.1021/acs.langmuir.2c01397] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Polymer micromaterials in a liquid or gel phase covered with a surfactant membrane are widely used materials in pharmaceuticals, cosmetics, and foods. In particular, cell-sized micromaterials of biopolymer solutions covered with a lipid membrane have been studied as artificial cells to understand cells from a physicochemical perspective. The characteristics and phase transitions of polymers confined to a microscopic space often differ from those in bulk systems. The effect that causes this difference is referred to as the cell-size space effect (CSE), but the specific physicochemical factors remain unclear. This study introduces the analysis of CSE on molecular diffusion, nanostructure transition, and phase separation and presents their main factors, i.e., short- and long-range interactions with the membrane surface and small volume (finite element nature). This serves as a guide for determining the dominant factors of CSE. Furthermore, we also introduce other factors of CSE such as spatial closure and the relationships among space size, the characteristic length of periodicity, the structure size, and many others produced by biomolecular assemblies through the analysis of protein reaction-diffusion systems and biochemical reactions.
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Affiliation(s)
- Miho Yanagisawa
- Graduate School of Science, The University of Tokyo, Hongo 7-3-1, Bunkyo, Tokyo 113-0033, Japan
| | - Chiho Watanabe
- School of Integrated Arts and Sciences, Graduate School of Integrated Sciences for Life, Hiroshima University, Kagamiyama 1-7-1, Higashi-Hiroshima 739-8521, Japan
| | - Natsuhiko Yoshinaga
- Mathematical Science Group, WPI Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, Katahira 2-1-1, Aoba-Ku, Sendai 9808577, Japan
- MathAM-OIL, National Institute of Advanced Industrial Science and Technology, Sendai 980-8577, Japan
| | - Kei Fujiwara
- Department of Biosciences & Informatics, Keio University, Yokohama 223-8522, Japan
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Crowding and confinement act in concert to slow DNA diffusion within cell-sized droplets. iScience 2022; 25:105122. [PMID: 36185357 PMCID: PMC9523355 DOI: 10.1016/j.isci.2022.105122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 08/27/2022] [Accepted: 09/08/2022] [Indexed: 11/20/2022] Open
Abstract
Dynamics of biological macromolecules, such as DNA, in crowded and confined environments are critical to understanding cellular processes such as transcription, infection, and replication. However, the combined effects of cellular confinement and crowding on macromolecular dynamics remain poorly understood. Here, we use differential dynamic microscopy to investigate the diffusion of large DNA molecules confined in cell-sized droplets and crowded by dextran polymers. We show that confined and crowded DNA molecules exhibit universal anomalous subdiffusion with scaling that is insensitive to the degree of confinement and crowding. However, effective DNA diffusion coefficients Deff decrease up to 2 orders of magnitude as droplet size decreases—an effect that is enhanced by increased crowding. We mathematically model the coupling of crowding and confinement by combining polymer scaling theories with confinement-induced depletion effects. The generality and tunability of our system and models render them applicable to elucidating wide-ranging crowded and confined systems. DNA diffusion measured in cell-sized droplets with differential dynamic microscopy Combination of crowding and confinement leads to subdiffusion and slowing Diffusion coefficients of DNA decrease strongly with decreasing droplet size Polymer scaling theories and depletion effects predict observed dynamics
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Watanabe C, Yanagisawa M. Evaporation Patterns of Dextran-Poly(Ethylene Glycol) Droplets with Changes in Wettability and Compatibility. Life (Basel) 2022; 12:life12030373. [PMID: 35330124 PMCID: PMC8954583 DOI: 10.3390/life12030373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 02/23/2022] [Accepted: 03/01/2022] [Indexed: 11/16/2022] Open
Abstract
The dextran−PEG system is one of the most famous systems exhibiting phase separation. Various phase behaviors, including the evaporation process of the dextran−PEG system, have been studied in order to understand the physicochemical mechanism of intracellular phase separation and the effect of condensation on the origin of life. However, there have been few studies in dilute regime. In this study, we focused on such regimes and analyzed the pattern formation by evaporation. The specificity of this regime is the slow onset of phase separation due to low initial concentration, and the separated phases can have contrasting wettability to the substrate as evaporation progresses. When the polymer concentration is rather low (<5 wt%), the dextran−PEG droplets form a phase-separated pattern, consisting of PEG at the center and dextran ring of multiple strings pulling from the ring. This pattern formation is explained from the difference in wettability and compatibility between dextran and PEG upon condensation. At the initial dilute stage, the dextran-rich phase with higher wettability accumulates at the contact line of the droplet to form a ring pattern, and then forms multiple domains due to density fluctuation. The less wettable PEG phase recedes and pulls the dextran domains, causing them to deform into strings. Further condensation leads to phase separation, and the condensed PEG with improved wettability stops receding and prevents a formed circular pattern. These findings suggest that evaporation patterns of polymer blend droplets can be manipulated through changes in wettability and compatibility between polymers due to condensation, thus providing the basis to explore origins of life that are unique to the process of condensate formation from dilute systems.
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Affiliation(s)
- Chiho Watanabe
- School of Integrated Arts and Sciences, Graduate School of Integrated Sciences for Life, Hiroshima University, Kagamiyama 1-7-1, Higashi-Hiroshima 739-8521, Japan
- Correspondence:
| | - Miho Yanagisawa
- Komaba Institute for Science, Graduate School of Arts and Sciences, The University of Tokyo, Komaba 3-8-1, Tokyo 153-8902, Japan;
- Universal Biology Institute, Graduate School of Arts and Sciences, The University of Tokyo, Komaba 3-8-1, Tokyo 153-8902, Japan
- Department of Physics, Graduate School of Science, The University of Tokyo, Hongo 7-3-1, Tokyo 113-0033, Japan
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7
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Shinohara E, Watanabe C, Yanagisawa M. Perpendicular alignment of the phase-separated boundary in adhered polymer droplets. SOFT MATTER 2021; 17:9499-9506. [PMID: 34617089 DOI: 10.1039/d1sm01180d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
We investigated the effect of the adhered interface on the phase separation pattern using two or three adhered droplets containing a binary solution of poly(ethylene glycol) and gelatin. Under the experimental conditions, single domains of the gelatin-rich phase exhibited partial wetting to the droplet adhered interface (DAI) and nonadhered droplet surface. In the case of isolated spherical droplets, the location of the phase separation interface (PSI) of the domains was completely random owing to spatial symmetry. In the adhered droplets, the random orientation of the PSI was observed when the PSI did not contact the DAI. On the other hand, when the PSI contacted the DAI, the PSI was aligned perpendicular to the DAI. Frequency analysis showed that whether the PSI contacts the DAI is purely stochastic. However, the PSI alignment perpendicular to the DAI increases significantly with three adhered droplets, suggesting that the probability increases with increasing DAI area ratio. We explain this perpendicular pattern by the minimization of the interfacial energy and kinetics with a change in the wetting contact angle. These findings will facilitate the research on the phase separation of polymer solutions inside nonspherical micrometric spaces.
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Affiliation(s)
- Eriko Shinohara
- Komaba Institute for Science, The University of Tokyo, Komaba 3-8-1, Meguro, Tokyo 153-8902, Japan.
- Department of Applied Physics, Tokyo University of Agriculture and Technology, Naka-cho 2-24-16, Koganei, Tokyo 184-8588, Japan
| | - Chiho Watanabe
- Komaba Institute for Science, The University of Tokyo, Komaba 3-8-1, Meguro, Tokyo 153-8902, Japan.
- Graduate School of Integrated Sciences for Life, School of Integrated Arts and Sciences, Hiroshima University, Kagamiyama 1-7-1, Higashi-Hiroshima, Hiroshima 739-8521, Japan
| | - Miho Yanagisawa
- Komaba Institute for Science, The University of Tokyo, Komaba 3-8-1, Meguro, Tokyo 153-8902, Japan.
- Department of Basic Science, The University of Tokyo, Komaba 3-8-1, Meguro, Tokyo 153-8902, Japan
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Versatility of Reverse Micelles: From Biomimetic Models to Nano (Bio)Sensor Design. Processes (Basel) 2021. [DOI: 10.3390/pr9020345] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
This paper presents an overview of the principal structural and dynamics characteristics of reverse micelles (RMs) in order to highlight their structural flexibility and versatility, along with the possibility to modulate their parameters in a controlled manner. The multifunctionality in a large range of different scientific fields is exemplified in two distinct directions: a theoretical model for mimicry of the biological microenvironment and practical application in the field of nanotechnology and nano-based sensors. RMs represent a convenient experimental approach that limits the drawbacks of the conventionally biological studies in vitro, while the particular structure confers them the status of simplified mimics of cells by reproducing a complex supramolecular organization in an artificial system. The biological relevance of RMs is discussed in some particular cases referring to confinement and a crowded environment, as well as the molecular dynamics of water and a cell membrane structure. The use of RMs in a range of applications seems to be more promising due to their structural and compositional flexibility, high efficiency, and selectivity. Advances in nanotechnology are based on developing new methods of nanomaterial synthesis and deposition. This review highlights the advantages of using RMs in the synthesis of nanoparticles with specific properties and in nano (bio)sensor design.
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