Oda Yoshihisa, Hirata Aiko, Sano Toshio, Fujita Tomomichi, Hiwatashi Yuji, Sato Yoshikatsu, Kadota Akeo, Hasebe Mitsuyasu, Hasezawa Seiichiro
Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwanoha 5-1-5, Kashiwa, Chiba 277-8562, Japan.
Plant Cell Physiol. 2009 Apr;50(4):855-68. doi: 10.1093/pcp/pcp031. Epub 2009 Feb 27.
Eukaryotic cells have developed several essential membrane components. In flowering plants, appropriate structures and distributions of the major membrane components are predominantly regulated by actin microfilaments. In this study, we have focused on the regulatory mechanism of vacuolar structures in the moss, Physcomitrella patens. The high ability of P. patens to undergo homologous recombination enabled us stably to express green fluorescent protein (GFP) or red fluorescent protein (RFP) fusion proteins, and the simple body structure of P. patens enabled us to perform detailed visualization of the intracellular vacuolar and cytoskeletal structures. Three-dimensional analysis and high-speed time-lapse observations revealed surprisingly complex structures and dynamics of the vacuole, with inner sheets and tubular protrusions, and frequent rearrangements by separation and fusion of the membranes. Depolymerization of microtubules dramatically affected these structures and movements. Dual observation of microtubules and vacuolar membranes revealed that microtubules induced tubular protrusions and cytoplasmic strands of the vacuoles, indicative of interactions between microtubules and vacuolar membranes. These results demonstrate a novel function of microtubules in maintaining the distribution of the vacuole and suggest a functional divergence of cytoskeletal functions in land plant evolution.
真核细胞已经进化出几种重要的膜成分。在开花植物中，主要膜成分的适当结构和分布主要受肌动蛋白微丝调节。在本研究中，我们聚焦于苔藓小立碗藓中液泡结构的调控机制。小立碗藓的同源重组能力很强，这使我们能够稳定表达绿色荧光蛋白（GFP）或红色荧光蛋白（RFP）融合蛋白，并且小立碗藓简单的身体结构使我们能够对细胞内的液泡和细胞骨架结构进行详细的可视化观察。三维分析和高速延时观察揭示了液泡惊人的复杂结构和动态变化，包括内部薄片和管状突起，以及通过膜的分离和融合频繁发生的重排。微管解聚显著影响了这些结构和运动。对微管和液泡膜的双重观察表明，微管诱导了液泡的管状突起和细胞质丝，这表明微管与液泡膜之间存在相互作用。这些结果证明了微管在维持液泡分布方面的新功能，并暗示了陆地植物进化过程中细胞骨架功能的功能分化。
