Institute of Dental Sciences, Faculty of Dental Medicine, Hebrew University-Hadassah Medical Center, Jerusalem, Israel.
J Phys Condens Matter. 2010 May 19;22(19):194110. doi: 10.1088/0953-8984/22/19/194110.
The active regulation of cellular forces during cell adhesion plays an important role in the determination of cell size, shape and internal structure. While on flat, homogeneous and isotropic substrates some cells spread isotropically, others spread anisotropically and assume elongated structures. In addition, in their native environment as well as in vitro experiments, the cell shape and spreading asymmetry can be modulated by the local distribution of adhesive molecules and topography of the environment. We present a simple elastic model, and experiments on stem cells to explain the variation of cell size with the matrix rigidity. In addition, we predict the experimental consequences of two mechanisms of acto-myosin polarization and focus here on the effect of the cell spreading asymmetry on the regulation of the stress-fiber alignment in the cytoskeleton. We show that when cell spreading is sufficiently asymmetric the alignment of acto-myosin forces in the cell increases monotonically with the matrix rigidity; however, in general this alignment is non-monotonic as shown previously. These results highlight the importance of the symmetry characteristics of cell spreading in the regulation of cytoskeleton structure and suggest a mechanism by which different cell types may acquire different morphologies and internal structures in different mechanical environments.
细胞黏附过程中细胞力学的主动调控对细胞大小、形状和内部结构的决定起着重要作用。在平坦、均一和各向同性的基底上，一些细胞呈各向同性铺展，而另一些细胞呈各向异性铺展，并呈现出伸长的结构。此外，在其天然环境以及体外实验中，细胞形状和铺展的不对称性可以通过局部黏附分子的分布和环境的形貌来调节。我们提出了一个简单的弹性模型，并通过干细胞实验来解释细胞大小随基质刚度的变化。此外，我们还预测了两种肌动球蛋白极化机制的实验结果，这里重点关注细胞铺展不对称性对细胞骨架中应力纤维排列的调节作用。结果表明，当细胞铺展具有足够的不对称性时，细胞内肌动球蛋白力的排列随着基质刚度的增加而单调增加；然而，一般来说，这种排列是非单调的，如前所述。这些结果强调了细胞铺展的对称性特征在细胞骨架结构调节中的重要性，并提出了一种机制，通过该机制，不同的细胞类型可以在不同的力学环境中获得不同的形态和内部结构。
