Yamashiro S, Yamakita Y, Ono S, Matsumura F
Department of Molecular Biology and Biochemistry, Rutgers University, Busch Campus, Piscataway, New Jersey 08855, USA.
Mol Biol Cell. 1998 May;9(5):993-1006. doi: 10.1091/mbc.9.5.993.
Fascin is an actin-bundling protein that is found in membrane ruffles, microspikes, and stress fibers. The expression of fascin is greatly increased in many transformed cells, as well as in specialized normal cells including neuronal cells and antigen-presenting dendritic cells. A morphological characteristic common to these cells expressing high levels of fascin is the development of many membrane protrusions in which fascin is predominantly present. To examine whether fascin contributes to the alterations in microfilament organization at the cell periphery, we have expressed fascin in LLC-PK1 epithelial cells to levels as high as those found in transformed cells and in specialized normal cells. Expression of fascin results in large changes in morphology, the actin cytoskeleton, and cell motility: fascin-transfected cells form an increased number of longer and thicker microvilli on apical surfaces, extend lamellipodia-like structures at basolateral surfaces, and show disorganization of cell-cell contacts. Cell migration activity is increased by 8-17 times when assayed by modified Boyden chamber. Microinjection of a fascin protein into LLC-PK1 cells causes similar morphological alterations including the induction of lamellipodia at basolateral surfaces and formation of an increased number of microvilli on apical surfaces. Furthermore, microinjection of fascin into REF-52 cells, normal fibroblasts, induces the formation of many lamellipodia at all regions of cell periphery. These results together suggest that fascin is directly responsible for membrane protrusions through reorganization of the microfilament cytoskeleton at the cell periphery.
Fascin是一种肌动蛋白束集蛋白,存在于膜皱襞、微刺和应力纤维中。Fascin在许多转化细胞以及包括神经元细胞和抗原呈递树突状细胞在内的特化正常细胞中表达大幅增加。这些高表达Fascin的细胞共有的一个形态学特征是形成许多膜突起,其中Fascin占主导。为了研究Fascin是否导致细胞周边微丝组织的改变,我们在LLC-PK1上皮细胞中表达Fascin,使其水平与转化细胞和特化正常细胞中的水平一样高。Fascin的表达导致形态、肌动蛋白细胞骨架和细胞运动性发生巨大变化:转染Fascin的细胞在顶端表面形成数量增加且更长更粗的微绒毛,在基底外侧表面延伸出片状伪足样结构,并显示细胞间接触紊乱。通过改良的博伊登小室检测时,细胞迁移活性增加了8至17倍。将Fascin蛋白显微注射到LLC-PK1细胞中会引起类似的形态学改变,包括在基底外侧表面诱导形成片状伪足以及在顶端表面形成数量增加的微绒毛。此外,将Fascin显微注射到REF-52细胞(正常成纤维细胞)中,会在细胞周边的所有区域诱导形成许多片状伪足。这些结果共同表明,Fascin通过重组细胞周边的微丝细胞骨架直接导致膜突起的形成。