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Ishii N, Noguchi K, Ikemoto MJ, Yohda M, Odahara T. Optimizing Exosome Preparation Based on Size and Morphology: Insights From Electron Microscopy. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2023; 29:2068-2079. [PMID: 37831006 DOI: 10.1093/micmic/ozad103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 08/14/2023] [Accepted: 09/08/2023] [Indexed: 10/14/2023]
Abstract
Extracellular vesicles (EVs), including exosomes, are crucial in intercellular communication, but differentiating between exosomes and microvesicles is challenging due to their similar morphology and size. This study focuses on multivesicular bodies (MVBs), where exosomes mature, and optimizes exosome isolation using transmission electron microscopy (TEM) for size information. Considering that EVs are nanocolloidal particles, a salt-free Bis-Tris buffer is found to maintain EV integrity better than phosphate-buffered saline (PBS). Dynamic light scattering (DLS) and TEM analysis confirm that intact exosome fractions under the salt-free Bis-Tris buffer condition exhibit polydispersity, including a unique population of <50 nm vesicles resembling intraluminal membrane vesicles (ILVs) in MVBs, alongside larger populations. This <50 nm population disappears in PBS or Bis-Tris buffer with 140 mM NaCl, transforming into a monodisperse population >100 nm. Immunoelectron microscopy also validates the presence of CD63, an exosome biomarker, on approximately 50 nm EVs. These findings provide valuable insights into exosome characterization and isolation, essential for future biomedical applications in diagnostics and drug delivery.
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Affiliation(s)
- Noriyuki Ishii
- Cellular and Molecular Biotechnology Research Institute, Department of Life Science and Biotechnology, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central-6, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan
- Electron Microscopy Facility, Open Research Facilities Station, Open Research Platform Unit, Tsukuba Innovation Arena (TIA) Central Office, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central-6, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan
- The United Graduate School of Agricultural Science, Gifu University, 1-1 Yanagido, Gifu, Gifu 501-1193, Japan
| | - Keiichi Noguchi
- Instrumentation Analysis Center, Tokyo University of Agriculture and Technology, 2-24-16 Naka, Koganei, Tokyo 184-8588, Japan
| | - Mitsushi J Ikemoto
- Health and Medical Research Institute, Department of Life Science and Biotechnology, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central-6, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan
- Graduate School of Science, Toho University, 2-2-1 Miyama, Funabashi, Chiba 274-8510, Japan
| | - Masafumi Yohda
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, 2-24-16 Naka, Koganei, Tokyo 184-8588, Japan
| | - Takayuki Odahara
- Biomedical Research Institute, Department of Life Science and Biotechnology, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central-6, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan
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Balleza D. Peptide Flexibility and the Hydrophobic Moment are Determinants to Evaluate the Clinical Potential of Magainins. J Membr Biol 2023; 256:317-330. [PMID: 37097306 DOI: 10.1007/s00232-023-00286-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2023] [Accepted: 04/05/2023] [Indexed: 04/26/2023]
Abstract
Using a flexibility prediction algorithm and in silico structural modeling, we have calculated the intrinsic flexibility of several magainin derivatives. In the case of magainin-2 (Mag-2) and magainin H2 (MAG-H2) we have found that MAG-2 is more flexible than its hydrophobic analog, Mag-H2. This affects the degree of bending of both peptides, with a kink around two central residues (R10, R11), whereas, in Mag-H2, W10 stiffens the peptide. Moreover, this increases the hydrophobic moment of Mag-H2, which could explain its propensity to form pores in POPC model membranes, which exhibit near-to-zero spontaneous curvatures. Likewise, the protective effect described in DOPC membranes for this peptide regarding its facilitation in pore formation would be related to the propensity of this lipid to form membranes with negative spontaneous curvature. The flexibility of another magainin analog (MSI-78) is even greater than that of Mag-2. This facilitates the peptide to present a kind of hinge around the central F12 as well as a C-terminal end prone to be disordered. Such characteristics are key to understanding the broad-spectrum antimicrobial actions exhibited by this peptide. These data reinforce the hypothesis on the determinant role of spontaneous membrane curvature, intrinsic peptide flexibility, and specific hydrophobic moment in assessing the bioactivity of membrane-active antimicrobial peptides.
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Affiliation(s)
- Daniel Balleza
- Laboratorio de Microbiología, Unidad de Investigación y Desarrollo en Alimentos, Instituto Tecnológico de Veracruz, Tecnológico Nacional de México, Veracruz, Mexico.
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Nakao H, Nagao M, Yamada T, Imamura K, Nozaki K, Ikeda K, Nakano M. Impact of transmembrane peptides on individual lipid motions and collective dynamics of lipid bilayers. Colloids Surf B Biointerfaces 2023; 228:113396. [PMID: 37311269 DOI: 10.1016/j.colsurfb.2023.113396] [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: 03/22/2023] [Revised: 05/15/2023] [Accepted: 06/05/2023] [Indexed: 06/15/2023]
Abstract
The fluid nature of lipid bilayers is indispensable for the dynamic regulation of protein function and membrane morphology in biological membranes. Membrane-spanning domains of proteins interact with surrounding lipids and alter the physical properties of lipid bilayers. However, there is no comprehensive view of the effects of transmembrane proteins on the membrane's physical properties. Here, we investigated the effects of transmembrane peptides with different flip-flop-promoting abilities on the dynamics of a lipid bilayer employing complemental fluorescence and neutron scattering techniques. The quasi-elastic neutron scattering and fluorescence experiments revealed that lateral diffusion of the lipid molecules and the acyl chain motions were inhibited by the inclusion of transmembrane peptides. The neutron spin-echo spectroscopy measurements indicated that the lipid bilayer became more rigid but more compressible and the membrane viscosity increased when the transmembrane peptides were incorporated into the membrane. These results suggest that the inclusion of rigid transmembrane structures hinders individual and collective lipid motions by slowing down lipid diffusion and increasing interleaflet coupling. The present study provides a clue for understanding how the local interactions between lipids and proteins change the collective dynamics of the lipid bilayers, and therefore, the function of biological membranes.
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Affiliation(s)
- Hiroyuki Nakao
- Department of Biointerface Chemistry, Faculty of Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan
| | - Michihiro Nagao
- National Institute of Standards and Technology Center for Neutron Research, Gaithersburg, MD 20899-6102, USA; Department of Materials Science and Engineering, University of Maryland, College Park, MD 20742-2115, USA; Department of Physics and Astronomy, University of Delaware, Newark, DE 19716, USA
| | - Takeshi Yamada
- Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society (CROSS), 162-1 Shirakata, Tokai, Naka, Ibaraki 319-1106, Japan
| | - Koki Imamura
- Graduate School of Science and Engineering, University of Toyama, 3190 Gofuku, Toyama 930-8555, Japan
| | - Koichi Nozaki
- Graduate School of Science and Engineering, University of Toyama, 3190 Gofuku, Toyama 930-8555, Japan
| | - Keisuke Ikeda
- Department of Biointerface Chemistry, Faculty of Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan
| | - Minoru Nakano
- Department of Biointerface Chemistry, Faculty of Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan.
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Hofmann KP, Lamb TD. Rhodopsin, light-sensor of vision. Prog Retin Eye Res 2023; 93:101116. [PMID: 36273969 DOI: 10.1016/j.preteyeres.2022.101116] [Citation(s) in RCA: 21] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Revised: 08/20/2022] [Accepted: 08/22/2022] [Indexed: 11/06/2022]
Abstract
The light sensor of vertebrate scotopic (low-light) vision, rhodopsin, is a G-protein-coupled receptor comprising a polypeptide chain with bound chromophore, 11-cis-retinal, that exhibits remarkable physicochemical properties. This photopigment is extremely stable in the dark, yet its chromophore isomerises upon photon absorption with 70% efficiency, enabling the activation of its G-protein, transducin, with high efficiency. Rhodopsin's photochemical and biochemical activities occur over very different time-scales: the energy of retinaldehyde's excited state is stored in <1 ps in retinal-protein interactions, but it takes milliseconds for the catalytically active state to form, and many tens of minutes for the resting state to be restored. In this review, we describe the properties of rhodopsin and its role in rod phototransduction. We first introduce rhodopsin's gross structural features, its evolution, and the basic mechanisms of its activation. We then discuss light absorption and spectral sensitivity, photoreceptor electrical responses that result from the activity of individual rhodopsin molecules, and recovery of rhodopsin and the visual system from intense bleaching exposures. We then provide a detailed examination of rhodopsin's molecular structure and function, first in its dark state, and then in the active Meta states that govern its interactions with transducin, rhodopsin kinase and arrestin. While it is clear that rhodopsin's molecular properties are exquisitely honed for phototransduction, from starlight to dawn/dusk intensity levels, our understanding of how its molecular interactions determine the properties of scotopic vision remains incomplete. We describe potential future directions of research, and outline several major problems that remain to be solved.
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Affiliation(s)
- Klaus Peter Hofmann
- Institut für Medizinische Physik und Biophysik (CC2), Charité, and, Zentrum für Biophysik und Bioinformatik, Humboldt-Unversität zu Berlin, Berlin, 10117, Germany.
| | - Trevor D Lamb
- Eccles Institute of Neuroscience, John Curtin School of Medical Research, The Australian National University, Canberra, ACT 2600, Australia.
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London E. Ordered Domain (Raft) Formation in Asymmetric Vesicles and Its Induction upon Loss of Lipid Asymmetry in Artificial and Natural Membranes. MEMBRANES 2022; 12:870. [PMID: 36135889 PMCID: PMC9503047 DOI: 10.3390/membranes12090870] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 09/01/2022] [Accepted: 09/03/2022] [Indexed: 06/16/2023]
Abstract
Lipid asymmetry, the difference in the lipid composition in the inner and outer lipid monolayers (leaflets) of a membrane, is an important feature of eukaryotic plasma membranes. Investigation of the biophysical consequences of lipid asymmetry has been aided by advances in the ability to prepare artificial asymmetric membranes, especially by use of cyclodextrin-catalyzed lipid exchange. This review summarizes recent studies with artificial asymmetric membranes which have identified conditions in which asymmetry can induce or suppress the ability of membranes to form ordered domains (rafts). A consequence of the latter effect is that, under some conditions, a loss of asymmetry can induce ordered domain formation. An analogous study in plasma membrane vesicles has demonstrated that asymmetry can also suppress domain formation in natural membranes. Thus, it is possible that a loss of asymmetry can induce domain formation in vivo.
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Affiliation(s)
- Erwin London
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA
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