Hotani H, Inaba T, Nomura F, Takeda S, Takiguchi K, Itoh T J, Umeda T, Ishijima A
Department of Molecular Biology, Graduate School of Science, Nagoya University, Furo-cho, Nagoya 464-8602, Japan.
Biosystems. 2003 Sep;71(1-2):93-100. doi: 10.1016/s0303-2647(03)00113-8.
Liposomes are micro-compartments made of lipid bilayer membranes possessing the characteristics quite similar to those of biological membranes. To form artificial cell-like structures, we made liposomes that contained subunit proteins of cytoskeletons: tubulin or actin. Spherical liposomes were transformed into bipolar or cell-like shapes by mechanical forces generated by the polymerization of encapsulated subunits of microtubules. On the other hand, disk- or dumbbell-shaped liposomes were developed by the polymerization of encapsulated actin. Dynamic processes of morphological transformations of liposomes were visualized by high intensity dark-field light microscopy. Topological changes, such as fusion and division of membrane vesicles, play an essential role in cellular activities. To investigate the mechanism of these processes, we visualized the liposomes undergoing topological transformation in real time. A variety of novel topological transformations were found, including the opening-up of liposomes and the direct expulsion of inner vesicles.
脂质体是由脂质双分子层膜构成的微区室，其特性与生物膜非常相似。为了形成人工细胞样结构，我们制备了含有细胞骨架亚基蛋白（微管蛋白或肌动蛋白）的脂质体。通过微管包封亚基聚合产生的机械力，球形脂质体转变为双极或细胞样形状。另一方面，包封的肌动蛋白聚合形成了盘状或哑铃状脂质体。脂质体形态转变的动态过程通过高强度暗场光学显微镜进行了可视化观察。膜泡的融合和分裂等拓扑变化在细胞活动中起着至关重要的作用。为了研究这些过程的机制，我们实时观察了经历拓扑转变的脂质体。发现了多种新颖的拓扑转变，包括脂质体的开放和内部囊泡的直接排出。
