529 Study on the Reproducibility of Stress Fiber Orientation in Aortic Smooth Muscle Cells : Effects of Microtubules and Focal Adhesions
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Stress fibers (SFs) play essential roles in various cellular functions such as cell movement, shape maintenance and cell division. In addition, changes in the mechanical environment induce reorganization of the SFs. Recently, we noticed that the SF networks reappeared following their temporal disruption with cytochalasin D looked similar to those before disruption in rat aortic smooth muscle cells (RASMs). This indicates that the cells may have a memory of SF orientation. The aim of this study was to clarify the mechanism of the memory particularly focusing on the effects of microtubules (MTs) and focal adhesions (FAs) during the reorganization process of SFs. Firstly, we preconditioned the cells with cyclic stretch to make their SFs align in a uniform direction. After cyclic stretching, we depolymerized SFs completely with cytochalasin D for 3 h, and let them repolymerize in the drug free medium for 3 h. To know the effects of MTs during the SF repolymerization, we depolymerized MTs with colchicine. FAs were observed with a surface reflective interference contrast microscopy. In the presence of MTs, repolymerized SFs appeared in random orientation with newly formed FM, while FM were not destroyed and the alignment of SFs was conserved in the absence of MTs. The conservation of FAs might serve as a memory of SF alignment.
