The role of tropomyosin in regulating actin filament dynamics in fission yeast

肌动蛋白是一种重要的细胞骨架蛋白，在目前研究的所有真核生物中都是保守的。正是肌动蛋白聚合成动态细丝的能力，使细胞的生长甚至运动迅速受到细胞内和细胞外需求的影响。在细胞信号传递时，肌动蛋白聚合形成丝状或F-肌动蛋白，形成索状和晶格结构，在酵母菌中称为斑块。这些肌动蛋白电缆已被证明在大量细胞过程中发挥作用，包括细胞极性；胞质分裂；细胞生长和运动；提供皮质张力；内吞；以及充当分子马达(肌球蛋白)可以沿其行进的“路径”。肌动蛋白的功能在酵母中是保守的，并形成主要定位于细胞生长区域的线束和斑块，促进细胞在间期增大，或在胞质分裂期间分裂。裂殖酵母，裂殖酵母，呈圆柱形，在细胞极点以极化方式生长。在间期，肌动蛋白主要定位于这些生长细胞极处的补丁结构和贯穿细胞质的肌动蛋白缆线。在有丝分裂期间，肌动蛋白电缆作为细胞动态环的主要组成部分存在，细胞动态环收缩以便于细胞分裂。这个项目利用这种实验上容易驯化的有机体所允许的跨学科方法来确定肌动蛋白细丝在调节和维持极化细胞生长中所起的作用。使用多功能的分裂酵母模型系统使我们不仅能够在体内和体外环境中检查肌动蛋白细丝，而且允许我们利用突变体来调节细丝的动力学以及它们与马达蛋白相互作用的能力。这样，就有可能阐明它们在细胞内的功能(S)。

Actin is an essential cytoskeletal protein which is conserved in all eukaryotic organisms examined to date. It is actin's ability to polymerise into dynamic filaments which allows a cell's growth and even movement to be rapidly affected by both intra- and extra-cellular demands. Upon cellular signalling the actin polymerises to form filamentous or F-actin which form both cables and lattice structures, known as patches in yeasts. These actin cables have been shown to have a role in a large number of cellular processes which include cell polarity; cytokinesis; cell growth and movement; providing cortical tension; endocytosis; and acting as 'pathways' along which molecular motors (myosins) can travel. Actin's functions are conserved within yeasts, and forms cables and patches which localise predominantly to regions of cell growth, facilitating the cells increase in size during interphase, or division during cytokinesis. The fission yeast, Schizosaccharomyces pombe, is cylindrical in shape, with growth occurring in a polarised manner at the cell pole. Actin is seen to localised predominantly to patch structures at these growing cell poles and to actin cables throughout the cytoplasm during interphase. During mitosis actin cables exist as a major component of the cytokinetic ring, which contracts in order for a cell to divide. This project make use of the cross-discipline approaches allowed by this experimentally tractable organism to determine the role actin filaments play in regulating and maintaining polarised cell growth. Using the versatile fission yeast model system allows us to not only examine actin filaments in both an in vivo and in vitro context, but allows us to make use of mutants to modulate filaments' dynamics as well as their ability to interact with motor proteins. Thus it will be possible to elucidate their function(s) within the cell.