Shutova M S, Aleksandrova A Iu
Tsitologiia. 2010;52(1):41-51.
Polymerization of microfilaments and their subsequent rearrangements under control of actin-myosin interactions are two main processes underlined morphogenetic reactions of cells. We studied their role during spreading of normal and transformed REF52tetRas fibroblasts with adjustable ras oncogene expression. Treatment with inhibitors of cell contractility (Y27532 or blebbistatin) led to disappearance of actin bundles and focal adhesions, but both normal and transformed cells preserved high pseudopodial activity. Spreading was considerably accelerated in normal cells and less accelerated in ras-transformed cells under these conditions. When actin polymerization was suppressed with low concentrations of latrunculin A, stress-fibrills and focal contacts were preserved, but lamellipodial activity was lost in normal cells, so spreading was dramatically inhibited. In the case of transformed fibroblasts, actin bundles and focal adhesions virtually disappeared, but pseudopofial activity was not lost and spreading was suppressed to a lesser extent. Therefore, the most essential process in regulation of cell spreading and polarization is microfilament polymerization at the leading edge. Incidentally, ras-transformed cells are less sensitive to inhibitors affecting cytoskeletal structure than non-transformed ones. Possible mechanisms underlying these diversities are discussed.
微丝的聚合及其在肌动蛋白-肌球蛋白相互作用控制下的后续重排是细胞形态发生反应的两个主要过程。我们研究了它们在具有可调节ras癌基因表达的正常和转化的REF52tetRas成纤维细胞铺展过程中的作用。用细胞收缩抑制剂（Y27532或blebbistatin）处理导致肌动蛋白束和粘着斑消失，但正常细胞和转化细胞均保持较高的伪足活性。在这些条件下，正常细胞的铺展明显加速，而ras转化细胞的铺展加速程度较小。当用低浓度的Latrunculin A抑制肌动蛋白聚合时，应力纤维和粘着接触得以保留，但正常细胞的片状伪足活性丧失，因此铺展受到显著抑制。对于转化的成纤维细胞，肌动蛋白束和粘着斑几乎消失，但伪足活性未丧失，铺展受到的抑制程度较小。因此，调节细胞铺展和极化的最关键过程是前缘的微丝聚合。顺便说一句，ras转化细胞对影响细胞骨架结构的抑制剂的敏感性低于未转化细胞。讨论了这些差异背后的可能机制。
