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2000 Fiscal Year Final Research Report Summary

Morphological changes of liposomes caused by actin assembly : the effect of actin binding proteins and surfactants.

Research Project

Project/Area Number 11680655
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field Biophysics
Research InstitutionNagoya University

Principal Investigator

TAKIGUCHI Kingo  Nagoya University, Graduate School of Science, Research Assistant, 大学院・理学研究科, 助手 (20262842)

Project Period (FY) 1999 – 2000
Keywordsliposome / actin / cytoskeleton / optical microscopy / membrane morphogenesis
Research Abstract

1.To study the morphogenesis of cells caused by the organization of their internal cytoskeletal network, we characterized the transformation of liposomes encapsulating actin and its crosslinking proteins, fascin, α-actinin, or filamin, using real-time high-intensity dark-field microscopy. The encapsulated G-actin polymerized into actin filaments and formed bundles or gels, depending on the type of actin-crosslinking protein that was co-encapsulated, causing various morphological changes of liposomes. The differences in morphology among transformed liposomes indicate that actin-crosslinking proteins determine liposome shape by organizing their specific actin networks. Morphological analysis reveals that the crosslinking manner, i.e. distance and angular flexibility between adjacent crosslinked actin filaments, is essential for the morphogenesis.
2.Gelsolin is one of the best known actin-binding proteins with activities regulated by calcium. We found that plasma gelsolin can be phosphorylated by using the kinase fraction isolated from mitotic HeLa cells. After this phosphorylation, gelsolin no longer requires Ca^<2+> for activity : it severs and subsequently caps actin filaments, and nucleates filament formation in Ca^<2+>-free solutions.
3.Dynamic behaviors of liposomes caused by interactions between liposomal membranes and surfactant were studied by direct, real-time observation using high-intensity dark-field microscopy. Solubilization of liposomes by surfactants is thought to be a catastrophic event akin to the explosion of soap bubbles in the air ; however, the actual process has not been clarified. We studied this process experimentally and found that liposomes exposed to various surfactants exhibited novel behavior, namely continuous shrinkage accompanied by intermittent quakes, release of encapsulated liposomes, opening-up, and inside-out topological inversion.

  • Research Products

    (12 results)

All Other

All Publications (12 results)

  • [Publications] HONDA Makoto: "Morphogenesis of liposomes encapsulating actin depends on the type of actin-crosslinking"Journal of Molecular Biology. 287巻. 293-300 (1999)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] TAKIGUCHI Kingo: "Artificial phosphorylation removes gelsolin's dependence on calcium"Cell Structure and Function. 25巻. 57-65 (2000)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] NOMURA Fumimasa: "Novel capabilities of liposomes for topological transformation"Proceedings of the National Academy of Sciences USA. 98巻. 2340-2345 (2001)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] SUEZAKI Yukio: "A statistical mechanical theory for the adsorption of protein to liposomal membranes"Biophysical Chemistry. 80巻. 119-128 (1999)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] NOMURA Fumimasa: "Morphological and topological transformations of lipid bilayer vesicles"Statistical Physics(M.Tokuyama,H.Stanley 編,American Institute of Physics). 426-434 (2000)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] NOMURA Fumimasa: "Dynamic transformation of liposomes revealed by dark-field microscopy"Studies in Surface Science and Catalysis(Y.Iwasawa,N.Oyama,H.Kunieda 編,Elsevier Sciences). 495-500 (2001)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Honda, M., Takiguchi, K., Ishikawa, S., and Hotani, H.: "Morphogenesis of liposomes encapsulating actin depends on the type of actin-crosslinking."Journal of Molecular Biology. 28. 293-300 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Suezaki, Y., Ichinose, H., Takiguchi, K., and Hotani, H.: "A statistical mechanical theory for the adsorption of protein to liposomal membranes."Biophysical Chemistry. 80. 119-128 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Takiguchi, K., Yamashiro-Matsumura, S., and Matsumura, F.: "Artificial phosphorylation removes gelsolin's dependence on calcium."Cell Structure and Function. 25. 57-65 (2000)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Nomura, F., Honda, M., Takeda, S., Umeda, T., Takiguchi, K., and Hotani, H.: "Morphological and topological transformations of lipid bilayer vesicles."Statistical Physics (M.Tokuyama, H.Stanley, eds, American Institute of Physics). 426-434 (2000)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Nomura, F., Nagata, M., Inaba, T., Hiramatsu, H., Hotani, H., and Takiguchi, K.: "Capabilities of liposomes for topological transformation."Proceedings of the National Academy of Sciences USA. 98. 2340-2345 (2001)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Nomura, F., Honda, M., Takeda, S., Takiguchi, K., and Hotani, H.: "Dynamic transformation of liposomes revealed by dark-field microscopy."Studies in Surface Science and Catalysis (Y.Iwasawa, N.Oyama, H.Kunieda, eds, Elsevier Sciences). 495-500 (2001)

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 2002-03-26  

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